Diesel fuel composition containing dimethyl formamide and a metal naphthenate



United States Patent 3,389,978 DIESEL FUEL COMPOSITION CONTAININGDIMETHYL FORMAMIDE AND A METAL NAPHTHENATE John S. Mann, Medina, andWilliam F. Reinhart Shaker Heights, Ohio, assignors to The Standard O1lCompany, Cleveland, Ohio, a corporation of Ohio No Drawing. Filed Mar.25, 1966, Ser. No. 537,281 5 Claims. (Cl. 44-57) ABSTRACT OF THEDISCLOSURE A diesel fuel additive containing 25-250 ppm. of dimethylformamide and up to 500 ppm. on the basis of the metal portion of amaterial selected from the group of barium, calcium, strontium, zinc andmagnesium naphthenates. The additive package improves nozzlecleanliness, increases the cetane number of the fuel and provides otherbenefits.

This invention relates to a novel diesel engine fuel compositioncontaining performance-improving amounts of a metal naphthenate anddimethyl formamide (DMF). Metal naphthenates found to be effective forthe purpose hereinafter described include barium, calcium, strontium,zinc and magnesium.

A metal naphthenate, as a diesel fuel additive, improves performance interms of nozzle cleanliness and thus lowers exhaust smoke and increasespower. Dimethyl formamide shortens the ignition delay period, which is ameasure of cetane number, and thereby improves the cetane rating-of thefuel. It has now been discovered that cetane-improving property ofdimethyl formamide is further enhanced by the metal naphthenate in thefuel additive composition.

Naphthenate soaps require some excess acid for fuel solubility, however,excess acid tends to etch injector nozzles. The addition of dimethylformamide increases the solubility of the naphthenate soap in dieselfuel without the need of excess acid, thereby protecting injectornozzles against acid etching. An additional advantage of the diesel fueloil additive composition resides in its ability to greatly reduce filterclogging caused by ice agglomeration.

By itself, dimethyl formamide has the disadvantage of promoting varnishformation and coking of the injector nozzles. The metal naphthenates, onthe other hand, function as detergents and thus are capable ofmaintaining the nozzles clean. When combined into an additive package,the desirable properties of the components are retained and enhanced,while the undesirable properties are suppressed.

The naphthenic acids used in preparing the naphthenate soaps areconveniently of petroleum origin. Naphthenic acids from other sourcesmay also be used at the disadvantage of higher cost. The usefulpetroleum-derived acids are principally those removed from thelubricating oil and gas oil fractions of petroleum which boil within therange from about 500 F. to about 1000 F. at atmospheric pressures. Theseacids normally contain from about 8 to about 30 carbon atoms permolecule and distill in the range of from about 250 F. to about 600 F.at 2 mm. of mercury absolute pressure. Such acids can range insaponification value from about 50 to about ice 300 mgs. of KOH per gramon an unsaponifiables-free basis. It is desirable that the soaps derivedfrom mixtures of such acids have an average saponification value below225 mgs. of KOH per gram.

For purposes of this invention, a metal naphthenate concentration levelof 100 to 200 ppm. based on the metal is preferred, the higher amountbeing required for complete cleanliness of a pintle-type nozzle, whilethe lesser amount is satisfactory in integral injectors. In general,amounts in excess of 500 p.p.m. cannot be economically justified.

The amount of dimethyl formamide employed is dependent upon theconcentration of the metal naphthenate. Equivalent amounts of DMF tometal as the naphthenate are desirable, however, from about 25 to 250p.p.m. of dimethyl formamide may be employed.

The diesel fuel additives were tested in a single cylinder and in amulticylinder diesel engine. In the single cylinder engine, each testwas run with an initially clean nozzle, and hourly readings were takenof engine performance. The engine conditions that were used were asfollows:

Compression ratio 15:1.

Engine speed 600 rpm.

Rate of fuel injection 9 milliliters per 60:5

seconds.

Injection timing 13,BTC.

Injector opening pressure 2000 p.s.i.

Injector jacket temperature 100 F.

Engine jacket temperature 212 F.

Inlet air temperature 150 F.

The properties of the diesel fuel employed are given in Table I.

TABLE I API gravity 35.4 Specific gravity at 60 F. 0.8477 Sulphur"Percent..- 0.24

Viscosity: 1

At 100 F. cks 2.245 At 210 F. -cks 0.9685 IBP F 365 5% F... 414 10% F425 20% F..- 444 30% F 458 40% F-.. 472 F 484 F 496 F-.. 511 F 528 F.-552 F 574 E.P. F-.. 583 Saturates Percent 66 Olefins o 5 Aromatics 29For the single cylinder tests, various mixtures of barium naphthenateand dimethyl formamide were added to the base fuel as indicated in TableII, and the engine was run on each treated fuel. The numbers recordedare the average of seven observations taken at timed intervals over aseven-hour period. The fuels were rated for exhaust smoke, ignition lag,and power. The lower the ratings for smoke or lag, the better theperformance while the higher the rating of power, the better theperformance.

As naphthenate (contains 11 weight percent barium).

The data in Table II indicate the improvement obtained with thecombination of barium naphthenate and dimethyl formamide over the basefuel. The data show that with 100 p.p.m. of barium as barium naphthenateby itself, the exhaust smoke is lower and power is increased, but thereis a greater time lag in ignition as compared with the base fuel. With100 p.p.m. of dimethyl formamide by itself, there is almost no change inexhaust smoke, ignition lag or power ratings. The greatest amount ofimprovement in all three ratings was obtained with the use of equivalentamounts of barium as barium naphthenate and dimethyl formamide.

A comparison of calcium and barium naphthenates in diesel fuel is shownin Table 111. These data were generated from the same single cylindertest described above.

The results obtained for both metal naphthenates in combination withdimethyl formamide are very similar. Though smoke, ignition lag andpower ratings are improved with 100 p.p.m. of either barium or calciumnaphthenate, the ratings are further improved with the presence ofdimethyl formamide.

The naphthenates of strontium, zinc and magnesium also were tested andcompared favorably with the results obtained from barium and calciumnaphthenates. From an economical standpoint, however, barium naphthenateis preferred.

In the multicylinder test, a General Motors 3-53 diesel truck engine wasused. The engine was operated for two hours under steady drivingconditions, i.e., 2000 r.p.m. at 75 HP, and then two hours undertrafiic" cycling conditions as follows:

14 seconds-650 r.p.m. idle 35 seconds1500 r.p.m. at 50 HP 21seconds-4200 rpm. at 38.5 HP

4 and then back to two hours of steady driving, etc., for a total run of400 hours. The base fuel used as the blank was the same one employed inthe single cylinder tests. The engine was run for 400 hours on the basefuel without the additives, and then for 400 hours on the same base fuelto which had been added p.p.m. of barium as barium naphthenate and 91p.p.m. of DMF. The injectors of this engine have eight ports throughwhich the fuel is sprayed. At the end of the run on the base fuel, atleast one port was completely plugged with carbonaceous material andseveral other ports were partially closed, so that the spray pattern wasdistorted.

With the barium naphthenate and DMF present, the nozzle was as clean aswhen the test was started, and the spray pattern remained unmodifiedafter 400 hours.

Various modifications of the instant invention will occur to thoseskilled in the art upon reading the foregoing disclosure. It is intendedthat all such modifications be covered which reasonably fall within thescope of the appended claims.

We claim:

1. A fuel additive composition consisting essentially of from about 25p.p.m. to about 250 p.p.m. of dimethyl formamide and a material in anamount of up to 500 p.p.m. 0n the basis of the metal portion, saidmaterial selected from the group consisting of barium, calcium,strontium, zinc, and magnesium naphthenates, and mixtures thereof.

2. The composition of claim 1 wherein the concentrations of dimethylformamide and the metal portion of said material are on equal weightbasis.

3. A diesel fuel oil containing a performance-improving additiveconsisting essentially of from about 25 p.p.m. to about 250 p.p.m. ofdimethyl formamide and 11p to 500 p.p.m. on the basis of the metalportion of a material selected from the group consisting of barium,calcium, strontium, zinc, and magnesium naphthenates, and mixturesthereof.

4. The diesel fuel oil of claim 3 in which the concentrations ofdimethyl formamide and the metal portion of said material are on equalweight basis.

5. The diesel fuel oil of claim 3 in which the concentrations ofdimethyl formamide and the metal of the metal naphthenate are on equalweight basis and in the range of about p.p.m. to about 200 p.p.m.

References Cited UNITED STATES PATENTS 2,258,297 10/1941 Miller et a1.44--57 XR 2,918,359 12/1959 Lovett et a1 447l XR FOREIGN PATENTS 205,8425/1955 Australia.

DANIEL E. WYMAN, Primary Examiner.

W. J. SHINE, Assistant Examiner.

